Sleeping through the night

The past 2 nights, Sarah has slept for 7+ hours, basically through the whole night. She has been sleeping from about 11:30 to roughly 5:00 or 5:30 fairly consistently, but the past 2 nights, it has stretched. And as a result of this, she is wide awake through most of the day.
She has also started to grow out of her 2 hour fussy time at night where she just screams for no apparent reason. This is the most trying time for me, although I know she just needs to be held and comforted. I really enjoy spending time with her, especially when she is happy and all curious about everything. I don't know what I would do without her.